A method for producing 2,2′-bis (trifluoromethyl)-4,4′-diaminobiphenyl, that may be abbreviated as TFMB hereunder, through benzidine rearrangement reaction of 3,3′-bis(trifluoromethyl) hydrazobenzene, that may be abbreviated as hydrazo compound hereunder, is already known.
For example, according to Journal of Polymer Science Part A: Polymer Chemistry, Vol. 37, 937-957 (1999), TFMB is synthesized by dissolving the above hydrazo compound in ethanol and dropping the ethanol solution into concentrated hydrochloric acid at the temperature of 0° C. However the yield of TFMB was low level as 17 mole % based on the hydrazo compound and was insufficient as an industrial manufacturing method.
In addition, according to Journal of Chemical Society, 1994-1998 (1953), TFMB is synthesized by dissolving the above hydrazo compound in ethanol and dropping the ethanol solution of the above hydrazo compound into diluted sulfuric acid. However the yield of TFMB was only 10% by mole and therefore this was also insufficient as an industrial manufacturing method.